<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            display: flex;
            width: 800px;
            height: 300px;
            background-color: pink;
            /* 主轴方向默认为水平向右 */
            /* flex-direction: row; */
            /* 水平翻转 */
            /* flex-direction: row-reverse; */
            /* 可以把主轴设成列 */
            /* flex-direction: column; */
            /* 列翻转 */
            flex-direction: column-reverse;
        }
        div span {
            width: 150px;
            height: 100px;
            background-color: skyblue;
        }
    </style>
</head>
<body>
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
    </div>
</body>
</html>